The invention concerns a method for submersed, anaerobic fermentation of substrates with microorganisms, as well as an apparatus for performance of the method.
Anaerobic fermentations are performed as a rule in agitator containers. The agitation is necessary so that the microorganisms do not deposit on the bottom of the container and thus become isolated from the content of substrate material which is supposed to be transformed. The agitation is also necessary to provide the microorganisms quickly enough with new untransformed substrate. Although the gaseous reaction products of the anaerobic fermentation do indeed on account of their buoyancy provide for a type of convection in the interior of the container, this is not ordinarily sufficient for a quick enough upheaval of substrate material. Owing to the slow movement of the substrate mass, fermentation times run more than 50 hours. Such fermentation times also do not work out to be less with use of the known energy-intensive mechanical stirring systems. In addition, with stirring mechanisms that lie in the interior of the container, there is an almost complete entry of kinetic energy into the substrate, which, in the form of heat, must be eliminated from the system.
Concerning this problem of eliminating the heat produced by mechanical stirring, a jet conveyor for a one-phase system in the form of a loop-reactor with interior revolution of the reactor contents has been suggested.